The invention relates to a printing-unit accessory that is engaged with a printing unit of a printing press, in an operating position of the accessory, and is removed from the vicinity of the printing unit, in at least one maintenance position of the accessory, the accessory being secured to the printing press by a pivoting mechanism.
Because the installation space of printing units, especially in offset printing presses, is needed for numerous required printing unit components, such as the inking unit and, as a rule, also the dampening unit, it is often not possible for accessories to be permanently installed. There is accordingly a need for accessories which can be brought into position selectively but can be removed for maintenance work or for changing printing plates or inks, so that this necessary work can be performed. at the printing unit.
U.S. Pat. No. 5,630,363 proposes disposing such an accessory on a pivot arm secured to the top of the printing unit, so that the accessory can be pivoted across the printing unit. However, a hindrance thereto is that the space at the top of the printing unit is often unavailable, either because other devices are already located there or space for such devices must be reserved. Furthermore, the device disclosed in this reference impedes accessibility to the inking unit and can collide with printing plate changers. Pivoting an accessory upwardly in this manner requires considerable space above the printing press and could not be used in rooms with low ceilings.
Another proposal has been made heretofore to pivot the accessory towards the side into a vertical position. However, because most accessories have to engage the inside of the printing unit, this proposal can be used for only a few applications. Just like the pivoting path proposed in the aforedescribed U.S. Pat. No. 5,630,363, the pivoting path into the vertical position requires considerable time, which is a problem especially because, for many types of work, such as changing printing plates, it would actually suffice to move the accessory only a short distance away from the printing unit.
It is accordingly an object of the invention, therefore, to provide an accessory of the type referred to at the introduction hereto, namely an accessory for a printing unit, that within the shortest possible time can be brought into a region of the printing press wherein it does not impede the work to be performed at the printing unit, because the requisite space is available and need not be reserved for other accessories.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a printing-unit accessory engaged with a printing unit of a printing press, in an operating position of the accessory, and removed from the vicinity of the printing unit, in at least one maintenance position of the accessory, comprising a pivoting mechanism securing the accessory to the printing press, the pivoting mechanism being disposed in a region of a side wall of the printing unit in a manner that the accessory is movable into a vertical position adjacent the side wall, and at least one linear guide disposed in front of the side wall so that the accessory is displaceable into a horizontal position distal from the printing unit.
In accordance with another feature of the invention, the accessory, before being pivoted into the vertical position thereof, is displaceable horizontally at least far enough so that it no longer engages in the printing unit.
In accordance with a further feature of the invention, the pivoting mechanism and the linear guide are disposed on a side of the side wall.
In accordance with an added feature of the invention, the accessory includes a centering device for positioning the accessory exactly in the operating position thereof.
In accordance with an additional feature of the invention, the accessory includes a locking device for locking the accessory with a retaining force in a centered position thereof.
In accordance with yet another feature of the invention, the centering device has at least one bolt engageable in a prism.
In accordance with yet a further feature of the invention, the centering device has at least one stop.
In accordance with yet an added feature of the invention, the locking device is at least one pneumatic element for pressing the accessory against contact faces of the centering device.
In accordance with yet an additional feature of the invention, the accessory includes a drive mechanism and a cam with a cam roller embodied for imparting a horizontal displacement to the accessory at an onset of an adjusting motion, and for thereafter providing the pivoting motion for disposing the accessory in the vertical position thereof.
In accordance with a concomitant feature of the invention, the accessory includes a spring for reinforcing the pivoting motion.
By the device according to the invention, it is possible to place the accessory into one of two maintenance positions, as needed. For many operations at the printing unit, and especially for printing plate changing, a horizontal displacement of the accessory suffices. By this horizontal displacement, the accessory is moved away from the cylinders in a direction parallel thereto. If a further printing unit follows in a multicolor printing press, the accessory device is moved into a corridor between printing units. The horizontal displacement requires only an extremely short time, so that the down time of the printing press, for example, for changing printing plates, is not increased in length, and thus there is no loss of press productivity. For major maintenance work, such as cleaning the printing unit, changing the rubber blanket, and so forth, the accessory can be moved into a region wherein it is entirely out of the way for this work, and wherein collision problems with other accessories do not arise, nor is the space taken up thereby and have to be reserved therefor, respectively. No further space above the printing unit is required by the device according to the invention, and thus it is possible to adhere to a machine height of approximately 2.60 m even for large printing presses, so that these machines can be used even in printing plants with a low ceiling height.
Because both horizontal displacement and pivoting of the accessory are possible, no problem is presented if an accessory engages in the printing unit. The embodiment according to the invention offers the opportunity that the accessory, before being pivoted into the vertical position thereof, is displaced horizontally at least so far that it no longer engages in the printing unit.
Expediently, it is proposed that the pivoting mechanism and the linear guide be disposed on the side of the side wall. Consequently, the control side is kept free, and the pivoted-away accessory presents the least hindrance, nor is it in the way if a worker wants to walk between the printing units.
Particularly if the accessories are imaging devices, such accessories must be positioned extremely precisely so that such an image will match with the press register. It is therefore proposed that the accessory be positioned exactly in the operating position by a centering device. It can also be proposed that a locking device lock the accessory in the centered position with a retaining force. As a result, any relative motion between the imaging device and the plate cylinder, for example, is precluded, and even vibrations cannot cause such a relative motion.
An embodiment of the invention provides for the centering device to have at least one bolt that engages a prism. Because of the horizontal alignment of the prism in the bolt, exact horizontal positioning can be attained, which is especially important for imaging units. For an exact alignment vertically, provision can be made for the centering device to have at least one stop. This stop is expediently spaced apart vertically from the prism. One embodiment of the locking device provides for it to be at least one pneumatic element, which presses the accessory against contact faces of the centering device.
An embodiment of a device for performing the adjusting motions of the accessory device calls for a drive mechanism and a cam with a cam roller to be provided, and embodied in such a manner that they impart the horizontal displacement to the accessory at the onset of the adjusting motion, and thereafter provide the pivoting motion for placing the accessory in the vertical position thereof. Because this construction requires only a drive mechanism, such as a single pneumatic cylinder, hydraulic cylinder or electric drive mechanism, it is especially simple and economical. If, in this construction, only the rectilinear part of the cam is traversed by the cam roller, then the horizontal displacement of the accessory into the horizontal maintenance position occurs. In this position, a printing plate change or similar work can, for example, be performed. For more complicated maintenance work, the cam roller traverses a cam section or length wherein the cam roller is pivoted 90xc2x0. In this way, with the same single drive mechanism, the pivoting motion is also performed in order to reach or attain the maintenance position wherein the accessory is disposed vertically in front of a side wall of the printing unit, and the printing unit is made available for major maintenance work.
For both of the embodiments mentioned hereinbefore and for other embodiments, it is expedient if a spring, preferably a gas compression spring, reinforces the pivoting motion. In the foregoing exemplary embodiment, this provides the advantage that no long levers for force transmission are needed between the cam roller and the accessory.
Another construction, wherein the pivoting motion of the accessory device is initiated manually, provides that the spring and force transmission be formed in a manner that the accessory pivots automatically into the vertical position, the instant that it is pivoted a predetermined angle, such as 30xc2x0, manually from the horizontal position. If this construction involves accessories which engage in the printing units, it is expedient not to enable the pivoting into the vertical position only if the accessory has been displaced so far horizontally that it not longer engages in the printing unit. In this embodiment, a drive may be provided for the horizontal displacement. This drive can of course also be provided manually, but an automatic drive mechanism, preferably one or two pneumatic cylinders, is much more expedient.
One material application is where the accessory is an imaging device, that is engaged with or thrown onto the plate cylinder in the operating position of the accessory. Such imaging devices may be a laser lighting unit for the plate cylinder or also a device disposed on the rubber blanket cylinder or printing cylinder to make impressions in the printed sheets, for example, in the form of sequential numbers or other individual impressions for the individual imprints. To that end, an ink jet unit or a numbering mechanism can be used, for example. Naturally, it is also possible, however, in this manner to provide other accessory devices for a printing unit, such as an additional inking or varnishing unit, a dryer, or measuring systems in the form of measuring beams, for example, for register or ink measuring.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an accessory for a printing unit, it is nevertheless. not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: